KR102690133B1 - How to produce rinsing liquid - Google Patents

Abstract

The present application discloses a method for producing an aqueous rinsing liquid in an electrochemical cell having an anode chamber with an anode and a cathode chamber with a cathode, the anode chamber and the cathode chamber being separated by a cation-selective membrane, the method comprising: a) feeding an aqueous anode chamber feedstock to an anode chamber, (b) feeding an aqueous cathode chamber feedstock comprising at least one electrolyte through a cathode chamber, and (c) forming a rinsing liquid in the cathode chamber. and applying a voltage to the anode and cathode, wherein step a, step b, and step c are performed at least partially simultaneously. Also disclosed is an apparatus suitable for performing these methods.

Description

How to produce rinsing liquid

The present invention relates to a method of producing a rinsing liquid, particularly, but not exclusively, for use in rinsing the surface of an item, to prevent build-up of static energy while preventing damage to the surface of the item. It relates to a method of producing rinsing liquid in a cell.

Semiconductor wafers are processed to create sub-microscopic features on the surface of the wafer, for example, during the fabrication of integrated circuits. Processing typically involves multiple wet processing steps, and wafers are typically rinsed and dried after such processing. Spinning of semiconductor wafers typically occurs during the spin-rinse-dry step of processing.

Deionized water has traditionally been used to rinse semiconductor wafers after processing. High quality deionized water has few impurities and therefore leaves no material on the wafer after rinsing. However, deionized water also has a very high resistivity (i.e. low conductivity). This creates a significant risk of increasing static charge on the wafer during rinsing. If the electrostatic charge rises to a sufficient level, undesirable discharges may occur. This discharge can damage features on the wafer and cause defects in integrated circuits formed on the wafer.

US 2006/0115774 A1 describes a method for eliminating or reducing the accumulation of electrostatic charges on semiconductor wafers during spin-rinse-drying of the wafers. This method uses a solution of dissolved carbon dioxide and ions or deionized water during rinsing to neutralize static charges on the wafer as it rotates. Carbon dioxide dissolved in deionized water increases the conductivity of the water so that the build-up of static charges is reduced or prevented.

As an alternative to using carbon dioxide dissolved in deionized water, US 9,090,854 describes the use of a dilute aqueous solution of ammonia or amine as a rinsing liquid for rinsing wafers. Rinsing solutions have a pH ranging from 8 to 10, thus providing a non-acidic rinsing solution as an alternative to acidic deionized water with carbon dioxide rinsing liquid.

More recently, US 2016/0362310 A1 specifically mentions that “electrolyzed water” is used for cleaning surfaces in semiconductor technology. A method for electrochemically producing electrolyzed water has been described. The described method uses an electrochemical cell with an anode chamber separated from the cathode chamber by an ion exchange membrane. Water passes through the cathode chamber, and water containing electrolyte passes through the anode chamber. When voltage is applied to the anode and cathode, electrolyzed water is formed in the cathode chamber. In particular, electrolytes such as ammonium ions are transferred from the anode chamber to the cathode chamber through the ion exchange membrane to form electrolyzed water.

US 6,143,163 describes a water electrolysis method to produce acidic and alkaline water, which is known to be effective in preventing dissolution of electrode materials. The applicant notes that when the power supply to the electrolysis cell is cut off, the anode and cathode assume a potential depending on the environment of the anode or cathode chamber respectively, leading to the generation of a reverse current. This reverse current causes reduction of the anode material in the anode chamber, oxidation of the cathode material and collector in the cathode chamber, and leads to metal dissolution and/or electrode deactivation (in this regard, US 6,143,163 refers to carbon-based electrodes Instead, metal-based electrodes were used - see column 6, rows 18 to 30). To overcome this problem, the applicant proposes to apply a voltage and/or current insufficient to cause electrolysis between the anode and cathode in a power-off state, but sufficient to prevent the generation of a reverse current. This document indicates that alkaline water can be produced by supplying pure water and/or ammonium hydroxide to the cathode chamber (see column 7, lines 45 to 54).

JPH 10-001794 describes an electrolytic cell for producing alkaline water, the cell having an anode chamber and a cathode chamber separated by a perfluorocarbon cation exchange membrane, the cathode compartment is made of fluoropolymer, and the cathode is platinum. and/or ruthenium oxide and the cathode current collector is made of zirconium. Similar to US 6,143,163, this document indicates that alkaline water can be produced by supplying pure water and/or ammonium hydroxide to the cathode chamber.

However, in both US 6,143,163 and JPH 10-001794 the method of introducing the electrolyte ammonium hydroxide is not specified (e.g. there is no disclosure of using a cathode chamber feedstock comprising ammonium hydroxide). Additionally, details of the components for supplying the anode chamber in the production of alkaline water are not given. In this regard, certain examples of US 6,143,163 use pure water as a feedstock for both the anode chamber and the cathode chamber, and certain examples of JPH 10-001794 both use pure water as a feedstock for the cathode chamber. Additionally, no document indicates the concentration of ammonium hydroxide (or more generally the electrolyte) or the effects of ammonium hydroxide.

JPH 08-144077, JP 2013/010988, GB 2287719, US 2010/0187129, WO 2017/203007, US 6,527,940 and US 2007/018638 also describe methods for electrolyzing water.

The present invention has been designed taking into account the above considerations.

Most generally, the present invention provides a method for producing rinsing liquid in an electrochemical cell by passing water with dissolved electrolyte through a cathode chamber and applying a voltage to the anode and cathode of the electrochemical cell.

In a first aspect, the invention provides a method for producing an aqueous rinsing liquid in an electrochemical cell having an anode chamber having an anode and a cathode chamber having a cathode, wherein the anode chamber and the cathode chamber are cation-selective. ) are separated by a membrane, and the method is: a. feeding an aqueous anode chamber feedstock to the anode chamber; b. Feeding an aqueous cathode chamber feedstock comprising at least one electrolyte through the cathode chamber; and c. and applying a voltage to the anode and cathode to form a rinsing liquid in the cathode chamber, wherein step a, step b, and step c are performed at least partially simultaneously.

The rinsing liquid produced by the method of the first aspect can be used as a rinsing liquid in rinsing the surface of an article, particularly the surface of a semiconductor wafer. As will be described in more detail below, the method of the first aspect may also control the concentration of electrolyte in the rinsing liquid while controlling the Oxidation Reduction Potential (ORP) of the rinsing liquid. In this way, the conductivity of the rinsing liquid can be maintained at a level sufficient to prevent the accumulation of static charges, as well as to prevent surface corrosion of the rinsed article by control of the ORP of the rinsing liquid. The pH of the electrolyzed water may also be selected independently.

Aqueous anode chamber feedstock is the liquid that is fed into the anode chamber before and while voltage is applied to the anode and cathode. As such, the aqueous anode chamber feedstock may also be referred to as the aqueous anode chamber feeding liquid or aqueous anode chamber inflow.

Similarly, the aqueous cathode chamber feedstock is a liquid that is fed into the cathode chamber before and while voltage is applied to the anode and cathode. As such, aqueous cathode chamber feedstock may also be referred to as aqueous cathode chamber feeding liquid or aqueous cathode chamber inlet.

The anode chamber feedstock and cathode chamber feedstock are typically fed to the anode chamber and cathode chamber, respectively, prior to application of step c of applying voltage. In this way, the anode chamber and cathode chamber may be filled with anode chamber feedstock and cathode chamber feedstock, respectively, before voltage is applied.

When a voltage is applied to the anode and cathode in step c, the anode chamber feedstock and cathode chamber feedstock enter the anode chamber and cathode chamber, respectively, typically causing a flow of liquid through the cathode chamber and the anode chamber. This flow of liquid typically causes the liquid to exit the anode and cathode chambers and exit (or outlets) of the anode and cathode chambers, respectively. The outlets of the anode chamber and/or cathode chamber may be at the top of the electrochemical cell. In this way, all gases generated within the anode chamber and cathode chamber may be removed from the electrochemical cell. Build-up of gases in electrochemical cells may create a safety hazard, for example when the gas is hydrogen gas.

Feeding of the anode chamber feedstock and cathode chamber feedstock involves the respective introduction of the feedstock into the anode chamber and cathode chamber, respectively. It is known that an electrolyte refers to a substance that produces an electrically conductive solution when dissolved in a polar solvent such as water.

In a second aspect, the invention provides an apparatus for producing an aqueous rinsing liquid, the apparatus comprising an electrochemical cell having an anode in the anode chamber and a cathode in the cathode chamber, the anode chamber and the cathode chamber having a cation-selective rinsing liquid. Separated by a membrane, the anode chamber includes an anode chamber inlet for receiving an anode chamber feedstock, the cathode chamber includes a cathode chamber feedstock for receiving a cathode chamber feedstock, and the aqueous cathode chamber feedstock is water. and at least one electrolyte, wherein the device includes an anode chamber feedstock source in fluid communication with the anode chamber inlet to provide an aqueous anode chamber feedstock to the anode chamber, and an anode chamber feedstock source to provide an aqueous cathode chamber feedstock to the cathode chamber. and a cathode chamber feedstock source in fluid communication with the cathode chamber inlet.

The anode chamber feedstock source is an anode chamber feedstock supply for providing anode chamber feedstock to the electrochemical cell. Similarly, the cathode chamber feedstock source is a cathode chamber feedstock supply for providing cathode chamber feedstock to the electrochemical cell.

In a third aspect, the invention provides a method for producing an aqueous rinsing liquid in an electrochemical cell having an anode chamber having an anode and a cathode chamber having a cathode, the anode chamber and the cathode chamber being separated by a cation-selective membrane. And here's how:

a. feeding an aqueous anode chamber feedstock to the anode chamber;

b. feeding an aqueous cathode chamber feedstock;

c. It includes applying a voltage to the anode and cathode,

Step a, step b, and step c are performed at least partially simultaneously,

d. Discharging the cathode chamber output liquid from the cathode chamber through the cathode chamber outlet during and/or after step c; and

e. A further step is to add at least one electrolyte to the cathode chamber output liquid to form an aqueous rinsing liquid.

The cathode chamber output liquid is the cathode chamber outflow from the cathode chamber. As such, the cathode chamber output liquid is the product of the cathode chamber feedstock (inlet, feeding liquid) after application of voltage to the anode and cathode.

In a fourth aspect, the invention provides an apparatus for producing an aqueous rinsing liquid, the apparatus comprising an electrochemical cell having an anode in an anode chamber and a cathode in a cathode chamber, wherein the anode chamber and the cathode chamber are cation-selective. Separated by an optical membrane, the anode chamber includes an anode chamber inlet for receiving anode chamber feedstock, the cathode chamber includes a cathode chamber feedstock inlet for receiving cathode chamber feedstock, and the cathode chamber includes a cathode chamber feedstock inlet. an anode chamber feedstock source in fluid communication with the anode chamber inlet for providing aqueous anode chamber feedstock to the anode chamber; a cathode chamber feedstock source in fluid communication with the cathode chamber inlet, and an electrolyte source for delivering electrolyte to the cathode chamber output liquid discharged from the cathode chamber through the cathode chamber outlet.

The invention includes combinations of the described aspects and preferred features except where such combinations are clearly not permitted or clearly avoided.

Embodiments illustrating the principles of the invention will now be discussed with reference to the accompanying drawings.
1 shows a schematic diagram of an electrochemical cell useful in the present invention.
Figure 2 shows a schematic diagram of an example of an apparatus for producing rinsing liquid according to the first and second aspects of the invention.
Figure 3 shows a schematic diagram of an example of an apparatus for producing rinsing liquid according to the third and fourth aspects of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS Aspects and embodiments of the invention will now be described with reference to the accompanying drawings. Additional aspects and embodiments will be apparent to those skilled in the art. All documents mentioned in this context are incorporated herein by reference.

The method and apparatus of the present invention uses an electrochemical cell to produce an aqueous rinsing liquid suitable for rinsing the surface of a semiconductor wafer in use. The electrochemical cell has an anode chamber and a cathode chamber.

anode chamber

The anode chamber typically includes anode chamber walls surrounding an anode chamber cavity containing the anode. In some embodiments, the anode is a diamond electrode. The use of diamond electrodes reduces the risk of metal contaminants such as platinum and palladium. The anode may have an active surface area ranging from 50 to 150 cm ² . For example, the active anode surface may have dimensions of 140 mm x 100 mm, providing an active surface area of 140 cm ² . The anode active surface may form the main plane of the anode. The depth of the anode may range from 1 to 5 mm, for example about 2 mm.

The anode chamber typically has an anode chamber inlet. The anode chamber inlet may be an anode chamber feedstock inlet for receiving aqueous anode chamber feedstock from an anode chamber feedstock source.

In certain embodiments, the aqueous anode chamber feedstock consists essentially of water. In this way, the only positive ions that may pass through the cation-selective membrane of the electrochemical cell from the anode chamber to the anode chamber are hydrogen ions. Hydrogen ions may combine with hydroxide ions in the cathode chamber to form water. More generally, using an aqueous anode chamber feedstock consisting essentially of water prevents non-targeted species from entering the cathode chamber through the anode chamber. This helps separate controlling the pH value and controlling the ORP of the rinsing liquid.

In one alternative embodiment, the aqueous anode chamber feedstock may consist of water and one or more electrolytes. In this embodiment, the cation-selective membrane would typically be impermeable to cations in the electrolyte. In this way, cations from the electrolyte in the anode chamber may not pass through the cation selective membrane of the electrochemical cell to the cathode chamber. The electrolytic composition of the liquid in the cathode chamber may remain constant.

In certain embodiments, the water in the anode chamber feed is deionized water or purified water.

The anode chamber inlet is typically in fluid communication with the anode chamber feedstock source to provide an aqueous anode chamber feedstock. The anode chamber feedstock source may be, for example, an anode chamber feedstock tank. The anode chamber feedstock tank may, when in use, contain aqueous anode chamber feedstock. The anode chamber feedstock source typically includes an inert gas inlet in fluid communication with the inert gas source to provide inert gas to the anode chamber feedstock source. In this way, the anode chamber feedstock may be under an inert atmosphere. For example, the anode chamber source may include an inert gas inlet in fluid communication with the nitrogen gas source.

The pressure at which the anode chamber feedstock is fed to the anode chamber inlet will depend on the desired flow rate of the anode chamber feedstock to the anode chamber inlet. The absolute inlet pressure at the anode chamber inlet may be up to 4 bar. The flow rate of anode chamber feedstock in the anode chamber may range from 0.5 to 10 liters per minute. In some embodiments, the flow rate of anode chamber feedstock in the anode chamber ranges from 1 to 5 liters per minute. In certain embodiments, the flow rate of anode chamber feedstock in the anode chamber ranges from 1.0 to 2.0 liters per minute.

In some embodiments, the anode chamber feedstock is mixed in the anode chamber. For example, the anode chamber feed may be turbulent. Mixing of the anode chamber feedstock in the anode chamber may be produced by the formation of bubbles in the anode when a voltage is applied to the anode and electrode. At higher voltages, more electrolysis will occur, more bubbles and more mixing will be created.

The anode chamber also typically includes an anode chamber outlet for discharging the anode chamber output liquid from the anode chamber. The anode chamber output liquid discharged from the anode chamber through the anode chamber outlet may be fed to a waste outlet for disposal of the liquid discharged from the anode chamber output liquid.

In certain embodiments, the anode chamber output liquid is fed back to the anode chamber feedstock source. The anode chamber output liquid may have essentially the same composition as the anode chamber feedstock. In this way, the anode chamber output liquid can be recycled to be used again as anode chamber feedstock. Refilling of anode chamber feedstock to the anode chamber feedstock source may also be minimized to save resources such as water. The anode chamber feedstock source may have an anode chamber output liquid inlet in fluid communication with the anode chamber outlet to receive the anode chamber output liquid.

Gases such as ozone may also be released from the anode chamber outlet. The device may also include an anode chamber output vent port to vent excess gases from the anode chamber outlet. When the anode chamber outlet is in fluid communication with the anode chamber feedstock source, the anode chamber output exhaust port may be located at the anode chamber feedstock source. For example, the anode chamber output exhaust port may be an anode chamber feedstock tank exhaust port included in the anode chamber feedstock tank. In certain embodiments, the anode chamber feedstock source includes an anode chamber output exhaust port and an inert gas inlet in fluid communication with the inert gas source. In this way, the inert gas may assist exhaust of gases released from the anode chamber outlet through the anode chamber outlet exhaust port.

cathode chamber

The cathode chamber typically includes cathode chamber walls surrounding a cathode chamber cavity containing the cathode. In some embodiments, the cathode is a diamond electrode. The use of diamond electrodes reduces the risk of metal contaminants such as platinum and palladium. The cathode may have an active surface area ranging from 50 to 150 cm ² . For example, the active cathode surface may have a size of 140 mm x 100 mm, providing an active surface area of 140 cm ² . The cathode active surface may form the main plane of the cathode. The depth of the cathode may range from 1 to 5 mm, for example about 2 mm.

The cathode chamber typically has a cathode chamber inlet. The cathode chamber inlet may be a cathode chamber feedstock inlet for receiving aqueous cathode chamber feedstock from a cathode chamber feedstock source. The water in the aqueous cathode chamber feedstock may be deionized or purified water.

The cathode chamber feedstock may include water and one or more electrolytes. In certain embodiments, the cathode chamber feedstock includes water and the only electrolyte.

The electrolyte may be any electrolyte useful for increasing the conductivity of water. In certain embodiments, the electrolyte is an amine of the formula NR ¹ R ² R ³ , where R ¹ , R ² and R ³ are independently selected from hydrogen and C _1-4 alkyl. In one specific embodiment, the electrolyte is ammonia. Aqueous ammonia solutions are also referred to as ammonium hydroxide solutions. In some embodiments, the cathode chamber feedstock is an ammonia solution or an ammonium hydroxide solution.

The concentration of the electrolyte or electrolytes in the aqueous cathode chamber feedstock may range from 30 micromolar to 3 millimolar. In this way, a relatively dilute electrolyte solution is used. In a specific embodiment, the aqueous cathode chamber feedstock is an ammonia solution having an ammonia concentration ranging from 30 micromolar to 3 millimolar.

Advantageously, using an aqueous cathode chamber feedstock with a relatively dilute ammonia concentration (e.g., in the range of 30 micromolar to 3 millimolar) allows the rinsing liquid to have a suitable conductivity, pH and (independently) very low corrosivity. ) It has an ORP and is produced reliably. In contrast, the inventors found that it is difficult to reliably produce a diluted ammonia-containing rinsing liquid in the cathode chamber by feeding ammonia into the anode chamber and relying on diffusion of ammonia through a cation-permeable membrane into the cathode chamber, and that the method thus obtained It was found that this resulted in poorer control of the measured ammonia concentration and the measured ORP. Additionally, relying on the transfer of ammonia from the anode chamber to the cathode chamber requires that a relatively more concentrated ammonia solution be supplied to the anode chamber, which can lead to corrosion of components (especially metal parts), increasing the risk of impurities. can increase.

In some embodiments, the cathode chamber feedstock has a pH value ranging from 7.5 to 10.5.

The cathode chamber inlet is typically in fluid communication with the cathode chamber feedstock source. The cathode chamber source may be any arrangement that allows delivery of cathode chamber feedstock to the cathode chamber inlet. For example, the cathode chamber feedstock source may include a cathode chamber feedstock tank for storing cathode chamber feedstock or a cathode chamber feedstock concentrate.

Cathode chamber feedstock concentrate is a more concentrated version of the cathode chamber feedstock. If the cathode chamber feedstock concentrate is present, it is diluted with water to form the cathode chamber feedstock before being introduced into the cathode chamber. In these embodiments, the device may include a dilution point between the cathode chamber inlet and a cathode chamber feedstock tank containing the cathode chamber feedstock concentrate. The dilution point may be an in-line dilution point. That is, water is introduced into the flow of cathode chamber feedstock concentrate to form the cathode chamber feedstock. The dilution point may have a cathode chamber feedstock inlet for receiving the cathode chamber feedstock concentrate, a dilution inlet for receiving water, and a cathode chamber feedstock outlet for effluent of a mixture of the cathode chamber feedstock concentrate and water. . In some embodiments, the device may have two or more dilution points. That is, the cathode chamber concentrate may be diluted several times before reaching the desired electrolyte concentration to form the cathode chamber feedstock.

In certain embodiments, the cathode chamber feedstock source includes a cathode chamber feedstock tank for receiving water and electrolyte feedstock to form a cathode chamber feedstock concentrate, and a cathode chamber feedstock tank during passage from the cathode chamber feedstock tank to the cathode chamber. and a dilution point located along the fluid path between the cathode chamber feedstock tank and the cathode chamber for dilution of the feedstock concentrate with water. In this embodiment, the dilution point typically includes a dilution inlet in fluid communication with a water source.

In this particular embodiment, 1 part by volume (pbv) electrolyte raw material (e.g., concentrated ammonia solution) may be fed into the cathode chamber feed raw material tank every 99 to 999 pbv of water. The cathode chamber feed concentrate may include 1 pbv of electrolyte feed for every 100 to 1000 pbv of cathode chamber feed concentrate. The cathode chamber feedstock concentrate may then be diluted at the dilution point ranging from 1 pbv of cathode chamber feedstock concentrate to 49 pbv of water to 1 pbv of cathode chamber feedstock concentrate to 499 pbv of water. In this manner, the cathode chamber feedstock may be formed. The cathode chamber feedstock may include 1 pbv of cathode chamber feedstock concentrate for every 50 to 500 pbv of cathode chamber feedstock.

In some embodiments, the cathode chamber feedstock source includes a headspace containing an inert gas atmosphere. For example, the headspace of the cathode chamber feedstock tank may contain an inert gas atmosphere. In certain embodiments, nitrogen gas is an inert gas. If present, the inert gas may be introduced through the inert gas inlet of the cathode chamber feedstock source. The cathode chamber feedstock source may also include a cathode chamber feedstock source exhaust port for venting gases from the cathode chamber feedstock source. In this way, the pressure within the cathode chamber feedstock source may be controlled.

The pressure at which the cathode chamber feedstock is fed into the cathode chamber inlet will depend on the desired flow rate of the cathode chamber feedstock into the cathode chamber inlet. The absolute inlet pressure at the cathode chamber inlet may be up to 4 bar. The flow rate of cathode chamber feedstock in the cathode chamber may range from 3 to 100 liters per minute. In some embodiments, the flow rate of cathode chamber feedstock in the cathode chamber may range from 4 to 60 liters per minute. In certain embodiments, the flow rate of cathode chamber feedstock in the cathode chamber may range from 5 to 50 liters per minute.

In some embodiments, the flow rate of the cathode chamber feedstock through the cathode chamber is at least twice the flow rate of the anode chamber feedstock through the anode chamber. In certain embodiments, the flow rate of the cathode chamber feedstock through the cathode chamber is at least three times the flow rate of the anode chamber feedstock through the anode chamber. The maximum absolute inlet differential pressure between the anode chamber inlet and the cathode chamber inlet may be 0.5 bar.

In some embodiments, the method of the present invention includes measuring the conductivity and/or pH of the cathode chamber feedstock before the cathode chamber feedstock enters the cathode chamber. In some embodiments, the apparatus of the present invention includes a conductivity device positioned between the cathode chamber feedstock source and the cathode chamber inlet to measure the conductivity and/or pH of the cathode chamber feedstock before the cathode chamber feedstock enters the cathode chamber. Includes a meter and/or pH meter. In this way, the electrolyte concentration of the cathode chamber feed can be monitored before voltage is applied. In certain embodiments, the conductivity and pH of the cathode chamber feedstock are measured before the cathode chamber feedstock enters the cathode chamber. In this embodiment, the device may include a conductivity meter and a pH meter positioned between the cathode chamber feedstock source and the cathode chamber inlet.

In each of the third and fourth aspects of the method and apparatus, the cathode chamber feedstock may consist essentially of water. In these aspects, the conductivity and/or pH of the rinsing liquid may be measured. That is, conductivity and/or pH may be measured after electrolyte is added to the aqueous cathode chamber output.

electrochemical cell

The inner walls of the anode chamber and cathode chamber may be any material that does not interfere with the electrolysis process. In a specific embodiment, the anode chamber walls and cathode chamber walls are polyvinylidene fluoride (PVDF).

The electrochemical cell contains a cation-selective membrane to allow cations to pass from the anode chamber to the cathode chamber. Ion-selective membranes are known per se. For example, a cation-selective membrane may be selected from the Nafion® range of membranes (DuPont). In one embodiment, the cation-selective membrane is Nafion®450.

The voltage applied to the anode and cathode may be up to 48 V. In some embodiments, the voltage applied to the anode and cathode ranges from 10 to 30 V. In certain embodiments, the voltage applied to the anode and cathode ranges from 15 to 25 V. In one embodiment, the voltage applied to the anode and cathode is about 20 V. In some embodiments, the current across the entire electrochemical cell is about 20 A.

The devices described herein may include an electrical source to provide current and voltage for the methods described herein. The electrical source may be any known electrical source, especially any electrical source known to provide current and voltage for electrochemical cells.

In some embodiments, the anode chamber outlet and/or cathode chamber outlet are located on the upper surface of the electrochemical cell. In this way, any gases generated from the electrolyte when voltage is applied to the anode and cathode may be vented from the anode chamber and/or cathode chamber, respectively. In certain embodiments, the anode chamber outlet and the cathode chamber outlet are located on the upper surface of the electrochemical cell.

In certain embodiments, the electrochemical cell is as described in US 2016/0362310 A1, the contents of which are expressly incorporated herein. For example, an electrochemical cell useful in the method and device of the present invention may be one of the electrochemical cells available from Condias GmbH (Germany). These cells typically use boron-doped diamond electrodes on a silicon substrate and are commercially available as DIACHEM® electrodes from Condias GmbH.

In the methods of the present invention, the electrochemical cell:

○ pH meter to measure the pH of the aqueous cathode chamber feedstock,

○ ORP sensor to measure the ORP of the rinsing liquid,

○ Liquid flow meters to control the flow rate of the aqueous cathode chamber feedstock and the aqueous anode chamber feedstock, and

○ may be part of a device that includes a controller in fluid communication with the pH meter, ORP sensor, and liquid flow meters, wherein the controller is responsive to data from the pH meter and/or ORP sensor to control the liquid flow meters and/or liquid flow meters of the device. The flow rate is adjusted via other parameters (e.g., applied voltage, current, and/or pulsing). Advantageously, devices of this type allow separate dynamic control of pH and ORP.

Aqueous cathode chamber output

The cathode chamber typically includes a cathode chamber outlet. Liquid in the cathode chamber is typically transferred from the cathode chamber inlet near the cathode or cathodes (as cathode chamber feedstock) to the cathode chamber outlet. The liquid coming from the cathode chamber outlet is an aqueous cathode chamber output. If the cathode chamber feedstock contains an electrolyte, the aqueous cathode chamber output forms a rinsing liquid.

In certain embodiments, the redox potential (ORP) of the aqueous cathode chamber output is 0 mV or negative. That is, the aqueous cathode chamber output may be neutral or reducing. In this way, the aqueous cathode chamber output may not corrode the semiconductor wafer.

In certain embodiments, the ORP of the aqueous cathode chamber output is -500 mV or less. In more specific embodiments, the ORP of the aqueous cathode chamber output is -550 mV or less. In certain embodiments, the ORP of the aqueous cathode chamber output ranges from -550 to -900 mV.

In some embodiments, the method of the present invention includes measuring the ORP of the cathode chamber output. In these embodiments, the device may include an ORP sensor to measure the ORP of the cathode chamber output. Measuring the ORP of the cathode chamber output liquid provides confirmation that the cathode chamber output is suitable to be a rinsing liquid for, for example, semiconductor wafers. ORP sensors are known per se. ORP sensors are electrochemical sensors, typically sensors that include a measuring electrode and a reference electrode. The measuring electrode is typically a noble metal electrode such as a platinum electrode or a gold electrode.

Typically, a sample or aliquot of the cathode chamber output is taken from the cathode chamber output to measure ORP. Samples may be discarded as waste after measuring ORP with an ORP sensor. Measurement of the cathode chamber output by an ORP sensor may contaminate the cathode chamber output, making the tested sample of the cathode chamber output unsuitable for returning to the bulk cathode chamber output. The ORP sensor may be placed in a branch line of the device located behind the cathode chamber outlet. That is, a separate ORP sensor channel may branch off from the main cathode chamber output channel to channel a sample of the cathode chamber output.

The rinsing liquid is formed when the aqueous cathode chamber output exits the cathode chamber where the cathode chamber feedstock contains electrolyte. That is, the rinsing liquid is formed when the aqueous cathode chamber output exits the cathode chamber in the first and second aspects. A rinsing liquid is formed when the aqueous cathode chamber output combines with the electrolyte in the third and fourth aspects.

In certain embodiments, a rinsing liquid is used to rinse semiconductor wafers. In some embodiments, the rinsing liquid has a conductivity of 10 μS/cm or greater.

Rinsing liquid may be used directly from the cathode chamber or may be stored in a rinsing liquid storage tank.

In certain embodiments, the device includes a rinsing liquid storage tank in fluid communication with the cathode chamber outlet for storage of rinsing liquid. In certain embodiments, the headspace of the rinsing liquid storage tank includes an inert gas atmosphere. For example, the headspace of the rinsing liquid storage tank contains a nitrogen gas atmosphere. If present, the inert gas may be introduced through the inert gas inlet of the rinsing liquid storage tank. The rinsing liquid storage tank may also include a rinsing liquid storage tank exhaust port to vent gases in the rinsing liquid storage tank. In this way, the pressure in the rinsing liquid storage tank may be controlled and, in particular, any hydrogen gas produced in the cathode chamber may be vented.

In certain embodiments, the rinsing liquid is stored in a rinsing liquid storage tank having a rinsing liquid storage tank exhaust port before being used as a rinsing liquid for rinsing a semiconductor wafer. The rinsing liquid may be stored in a rinsing liquid storage tank for up to 2 hours before being used as a rinsing liquid for rinsing semiconductor wafers.

In some embodiments, the method includes the additional step of rinsing the semiconductor wafer with a rinsing liquid. In certain embodiments, the semiconductor wafer is spun during the rinsing step with the rinsing liquid. The rinsing step may be performed in a wafer rinsing chamber. A wafer rinsing chamber may form part of the apparatus described herein. In some embodiments, the apparatus of the present invention may include a plurality of wafer rinsing chambers, each of which may be supplied with rinsing liquid from an electrochemical cell.

The wafer rinsing chamber may be in fluid communication with a rinsing liquid storage tank or may be in direct fluid communication with the cathode chamber outlet through a wafer rinsing chamber pipe. If the wafer rinsing chamber is in direct fluid communication with the cathode chamber outlet, the wafer rinsing chamber pipe will typically include a gas exhaust port to vent any excess gas, such as hydrogen gas, present in the rinsing liquid.

If any part of the device of the present invention is in fluid communication with another part of the device, any suitable connection may be used. For example, suitable pipes and conduits are known per se .

Figure 1 shows a schematic diagram of an electrochemical cell 2 useful in the present invention. The electrochemical cell is divided into an anode chamber (4) containing an anode (6) and a cathode chamber (8) containing a cathode (10). The anode chamber (4) and cathode chamber (8) are separated by a cation exchange membrane (12).

In use, the anode chamber feedstock of deionized water is fed into the anode chamber (4) through the anode chamber feedstock inlet (14). At the same time, the cathode chamber feedstock of diluted ammonia solution is fed into the cathode chamber (8) through the cathode chamber feedstock inlet (16). When the anode chamber feedstock and cathode chamber feedstock are in the electrochemical cell, a voltage of 10 to 12 V is applied across the anode (6) and cathode (10). The voltage catalyzes the electrochemical reaction and may reduce the redox potential of the diluted ammonia solution in the cathode chamber (8).

Anode chamber reaction: 3H ₂ O → O ₃ + 6H ⁺ + 6e ^-

Cathode chamber reaction: 6H ₂ O + 6e ^- → 3H ₂ + 6OH ^-

Hydrogen ions produced in the anode chamber 4 move across the cation exchange membrane 12 to combine with hydroxide ions produced in the cathode chamber 8 to form water molecules. The anode chamber 4 produces water and ozone, which are discharged from the anode chamber 4 through the anode chamber outlet 18.

There are minimal or no ammonium ions in the cathode chamber (8) moving across the cation exchange membrane (12). The combination of hydrogen ions from the anode chamber 4 and hydroxide ions from the cathode chamber 8 in the cathode chamber 8 results in the production of water molecules in the cathode chamber to replace the water molecules used in the cathode chamber reaction. It may occur. As such, the cathode chamber 8 may produce electrolyzed water with an ammonia concentration similar or substantially similar to the cathode chamber feedstock while lowering the redox potential below a threshold level. This allows the production of electrolyzed water useful as rinsing water because the conductivity of the rinsing liquid is controlled and damaging corrosion effects are reduced. Electrolyzed water is discharged through the cathode chamber outlet (20).

The use of a diluted ammonia solution as the cathode chamber feedstock, deionized water as the anode chamber feedstock, and a cation-permeable membrane in the electrochemical cell allows the rinsing liquid to have well-controlled (low) concentrations of ammonia, conductivity, pH, and ORP. produce it. The ability to control ammonia concentrations to low levels helps minimize/prevent damage (corrosion) to the surfaces of items being treated. Additionally, the use of deionized water in the anode chamber feedstock helps minimize the introduction of unwanted species (e.g., impurities) across the cation permeable membrane into the cathode chamber, which may otherwise affect performance. In contrast, as mentioned above, feeding an ammonia solution to the anode chamber to provide a diluted ammonia solution and relying on transfer of ammonia to the cathode chamber through a cation-permeable membrane results in fluctuations in ammonia concentration. It was found that the electrochemical cell needed to be supplied with relatively higher concentrations of ammonia solution, without providing reliable results.

Figure 2 shows a schematic diagram of one embodiment of the device of the second aspect of the invention. The apparatus includes the electrochemical cell 2 of FIG. 1, an anode chamber feedstock tank 52, a cathode chamber feedstock 54, and a rinsing liquid storage tank 56.

Anode chamber feedstock tank 52 contains deionized water as anode chamber feedstock. The anode chamber feedstock tank 52 is initially filled with deionized water from a deionized water source. However, the anode chamber feedstock tank 52 is also filled (when the device is in use) with water and ozone produced from the anode chamber 4. Ozone and water are discharged through the anode chamber and into the anode chamber feedstock tank 52 through the anode chamber outlet pipe 62. Ozone gas is released from the anode chamber feedstock tank 52 through the anode chamber feedstock tank exhaust port 64. Nitrogen gas is also introduced into the anode chamber feedstock tank 52.

In operation, deionized water anode chamber feedstock in anode chamber feedstock tank 52 is fed through anode chamber feedstock pipe 66 into the anode chamber feedstock inlet of anode chamber 4.

The cathode chamber feedstock tank 54 contains ammonia solution as the cathode chamber feedstock concentrate. The cathode chamber feedstock concentrate is formed in the cathode chamber feedstock tank 54 by dilution of approximately 15 molar ammonia solution and deionized water. 15 molar ammonia solution raw materials are diluted 100 to 1000 times. As such, the cathode chamber feedstock concentrate has a concentration ranging from 15 to 150 millimoles. In this embodiment, nitrogen gas is also added to the cathode chamber feedstock tank 54. A cathode chamber feedstock tank exhaust port 68 is present within the cathode chamber feedstock tank 54. In this way, the pressure within the cathode chamber feedstock tank 54 can be controlled.

The cathode chamber feedstock concentrate exits the cathode chamber feedstock tank 54 through the cathode chamber feedstock tank outlet 70. The cathode chamber feed concentrate is then diluted a second time with deionized water in a T-fitting (72). The cathode chamber feedstock concentrate is diluted in a range of 50 to 500 times. A second dilution is provided to the cathode chamber feedstock. The cathode chamber feedstock has an ammonia concentration ranging from 30 micromolar to 3 millimolar. Cathode chamber feedstock is fed within the cathode chamber to the cathode chamber feedstock inlet through cathode chamber feed pipe 74.

In operation, a voltage of 10 to 12 V is applied across the electrochemical cell 2 of the device of FIG. 2 . As discussed above, ozone and water are released from the anode chamber outlet and are recycled through the anode chamber outlet pipe 62 to the anode chamber feedstock tank 52.

An electrolytically diluted ammonia solution, such as rinsing liquid, is discharged from the cathode chamber outlet through the rinsing liquid pipe 76 into the rinsing liquid storage tank 56. As with the cathode chamber feedstock tank 54, nitrogen gas is also added to the rinsing liquid storage tank 56. A rinsing liquid storage tank exhaust port 78 is present within the electrolyzed water tank 56. In this way, the pressure within the rinsing liquid storage tank 56 can be controlled.

The rinsing liquid storage tank has a rinsing liquid storage tank outlet 80 for feeding rinsing liquid to one or more wafer rinsing chambers 82 so that the rinsing liquid is used as a rinsing liquid for rinsing one or more spinning semiconductor wafers.

Various pumps (84) assist the flow of liquids around the device. Additionally, multiple quality control points exist within the device. A portion of the cathode chamber feedstock is diverted to conductivity meter 86 and pH meter 88 instead of entering the cathode chamber. The conductivity and pH of the cathode chamber feedstock are measured and adjusted if necessary for dilution of the ammonia solution stock and/or cathode chamber feed concentrate. This can be automatically controlled by a controller. Additionally, an ORP sensor 90 is located between the rinsing liquid storage tank 56 and the wafer rinsing chamber 82. In this way, the ORP of the rinsing liquid may be monitored to ensure that the ORP is within acceptable limits. This can also be controlled by a controller.

Figure 3 shows an example of an alternative configuration of the third and fourth aspects of the invention. The configuration is approximately the same as that in FIG. 2. Electrochemical cell (102), anode chamber (104), cathode chamber (108), cation exchange membrane (112), anode chamber feedstock tank (152), rinsing liquid storage tank (156), anode chamber outlet pipe (162) , anode chamber feedstock tank exhaust port 164, anode chamber feedstock pipe 166, rinsing liquid pipe 176, rinsing liquid storage tank exhaust port 178, rinsing liquid storage tank outlet 180, wafer rinsing chamber Fields 182, pumps 184, and ORP sensor 190 are all similarly arranged. However, the cathode chamber feed pipe 174 is now connected to a chamber feed source of cathode deionized water only. A 15 molar ammonia solution raw material as electrolyte is now added to the rinsing liquid pipe 176 behind the cathode chamber outlet. In this way, ammonia electrolyte is added to form the rinsing liquid. A 15 molar ammonia solution raw material is added at the flow rate to provide a concentration of ammonia in the rinsing liquid ranging from 30 micromolar to 3 millimolar.

The features disclosed in the foregoing technology, or in the claims below, or in the accompanying drawings, as appropriate expressed in terms of a means for performing the disclosed function or a method or process for obtaining the disclosed results or in specific forms thereof, separately , or any combination of these features may be utilized to implement the present invention in various forms.

Although the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will become apparent to those skilled in the art given this disclosure. Accordingly, the exemplary embodiments of the invention presented above are to be considered illustrative and not limiting. Various changes to the described embodiments may be made without departing from the spirit and scope of the invention.

For the avoidance of doubt, all theoretical explanations provided herein are provided for the purpose of enhancing the reader's understanding. The inventors do not wish to be bound by any of these theoretical explanations.

All section headings used herein are for organizational purposes only and should not be construed as limiting the subject matter described.

Throughout this specification, including the following claims, unless the context otherwise requires, the words “comprise” and “include” and “comprises” “comprising” and Variations such as “including” will be understood to imply inclusion of a specified integer or step or group of integers or steps but not exclusion of any other integer or step or group of integers or steps. .

It should be noted that, as used in the specification and the appended claims, the singular forms “a”, “an” and “the” include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as “about” from one particular value, and/or “about” to another particular value. Where such ranges are expressed, other embodiments include from one specific value and/or to another specific value. Similarly, by use of the antecedent “about,” it will be understood that when values are expressed as approximations, a particular value forms another embodiment. The term “about” in relation to numerical values is optional and means, for example, +/- 10 %.

References

A number of publications are cited above to more completely describe and disclose the present invention and the prior art to which it relates. All citations to these references are provided below. Each of these references is incorporated herein in its entirety.

US 2006/0115774 A1

US 9,090,854

US 2016/0362310 A1

US 6,143,163

JPH10-001794

JPH08-144077

JP 2013/010988

GB2287719

US 2010/0187129

WO 2017/203007

US 6,527,940

US 2007/018638

Claims (18)

1. A method of producing an aqueous rinsing liquid in an electrochemical cell having an anode chamber with an anode and a cathode chamber with a cathode, wherein the anode chamber and the cathode chamber are separated by a cation-selective membrane, The above method is:
a. feeding an aqueous anode chamber feedstock consisting essentially of water into the anode chamber through an inlet of the anode chamber;
b. feeding an aqueous cathode chamber feedstock consisting essentially of an aqueous ammonia solution into the cathode chamber through an inlet of the cathode chamber; and
c. applying a voltage to the anode and the cathode to form a rinsing liquid in the cathode chamber, and
Wherein step a, step b, and step c are performed at least partially simultaneously. According to claim 1,
wherein the cathode chamber feedstock has a pH value ranging from 7.5 to 10.5. The method of claim 1 or 2,
A method of producing an aqueous rinsing liquid, wherein the total electrolyte concentration of the cathode chamber feedstock ranges from 30 micromolar to 3 millimolar. The method of claim 1 or 2,
A method of producing an aqueous rinsing liquid, wherein the flow rate of the anode chamber feedstock in the anode chamber ranges from 0.5 to 10 liters per minute. The method of claim 1 or 2,
A method of producing an aqueous rinsing liquid, wherein the flow rate of the cathode chamber feedstock in the cathode chamber ranges from 3 to 100 liters per minute. The method of claim 1 or 2,
wherein the anode chamber output liquid from step c is recycled to the anode chamber feedstock. The method of claim 1 or 2,
The redox potential of the electrolyzed water in the cathode chamber is -550 mV or more negative. The method of claim 1 or 2,
rinsing a spinning semiconductor wafer with the rinsing liquid from the cathode chamber produced in step c. The method of claim 1 or 2,
The electrochemical cell is,
a. A pH meter for measuring the pH of the aqueous cathode chamber feedstock,
b. ORP sensor for measuring the oxidation reduction potential (ORP) of the rinsing liquid,
c. liquid flow meters for controlling the flow rate of the aqueous cathode chamber feedstock and the aqueous anode chamber feedstock, and
d. is part of a device that includes a controller in communication with the pH meter, the ORP sensor, and the liquid flow meters, and
wherein the controller adjusts the flow rate through the liquid flow meters and/or other parameters of the device in response to data from the pH meter and/or the ORP sensor. In an apparatus for producing an aqueous rinsing liquid,
The device comprises an electrochemical cell having an anode in an anode chamber and a cathode in a cathode chamber, the anode chamber and the cathode chamber being separated by a cation-selective membrane,
The anode chamber includes an anode chamber inlet for receiving an anode chamber feedstock consisting essentially of water, and the cathode chamber includes a cathode chamber feedstock inlet for receiving an aqueous cathode chamber feedstock. consists essentially of an aqueous solution of ammonia, and
The apparatus includes an anode chamber feedstock source in fluid communication with the anode chamber inlet to provide an aqueous anode chamber feedstock to the anode chamber, and an anode chamber inlet to provide the aqueous cathode chamber feedstock to the cathode chamber. An apparatus for producing an aqueous rinsing liquid, further comprising a cathode chamber feedstock source in fluid communication with. According to claim 10,
The apparatus further comprises a wafer rinsing chamber in fluid communication with a cathode chamber outlet of the cathode chamber for receiving rinsing liquid produced in the cathode chamber and rinsing a semiconductor wafer with the rinsing liquid. A device for producing. According to claim 11,
The apparatus further comprises a rinsing liquid storage tank in fluid communication with the cathode chamber outlet for intermediate storage of the rinsing liquid. According to claim 12,
An apparatus for producing an aqueous rinsing liquid, wherein the rinsing liquid storage tank includes a rinsing liquid storage tank vent port for venting excess gas. The method according to any one of claims 10 to 13,
wherein the anode chamber has an anode chamber outlet in fluid communication with an anode chamber feedstock tank to recycle the anode chamber output as anode chamber feedstock. The method according to any one of claims 10 to 13,
The cathode chamber feedstock source includes a cathode chamber feedstock concentrate, and the device is configured to connect the cathode chamber feedstock source and the cathode to dilute the cathode chamber feedstock concentrate with water prior to entering the cathode chamber. An apparatus for producing an aqueous rinsing liquid, comprising a dilution point between the chamber inlets. The method according to any one of claims 10 to 13,
a. a pH meter for measuring the pH of the aqueous cathode chamber feedstock,
b. an ORP sensor for measuring the ORP of the rinsing liquid,
c. liquid flow meters for controlling the flow rate of the aqueous cathode chamber feedstock and the aqueous anode chamber feedstock, and
d. a controller in communication with the pH meter, the ORP sensor, and the liquid flow meters,
In use, the controller adjusts the flow rate through the liquid flow meters and/or other parameters of the device in response to data from the pH meter and/or the ORP sensor. Device. delete delete

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